Cellular telephones are currently being developed to take advantage of local area network (LAN) capabilities when placing/receiving calls from within the local-area network. For example, Motorola Inc. is developing a dual-mode phone that operates using both a wireless LAN (WLAN) protocol and a cellular protocol (e.g., GSM, CDMA, . . . , etc.). During operation, the WLAN is utilized for placing/receiving calls within the user's WLAN, while a wide-area network (WAN) (preferably a cellular network) is utilized for placing/receiving calls outside the user's WLAN.
As is evident, seamless mobility needs to be provided when roaming between the local and wide-area networks. For seamless mobility, there must be no ambiguity as to a telephone's location. In order to assure that all calls to the WLAN are properly routed to a user's telephone when outside WLAN coverage, all location updates must be made prior to handing over from the WLAN to the WAN. This is because for the majority of WLAN network configurations, WLAN coverage cannot be relied on for the delivery of location updates to the location database once the hand-out to the WAN has been committed. For example, local RF conditions change so rapidly (such as a door closing) that the subscriber device may not have a chance to send a location update over the WLAN before switching to the WAN network. If the location update is not completed before loss of WLAN network coverage, then the WLAN location information will be incorrect. This results in incoming calls to the subscriber being routed incorrectly by the WLAN. Therefore, a need exists for a method and apparatus for updating information within a communication system that allows for such information to be updated even when losing WLAN coverage.